Although there has been growing concern in recent years about an escalation in the use of LSD and other hallucinogens, little is known about the distribution of the use of these drugs in the United States population. In order to fill this gap, we used generalized additive models to analyze data from the 1988, 1990, and 1992 National Household Survey on Drug Abuse, to compare the age-specific prevalence of hallucinogen use by level of socio-economic indicators. In addition, we used survival analysis to compare patterns in the onset of use. Use of hallucinogens in the past year was highest at the age of 19 years for each of the NHSDA surveys, but use was not linked to enrollment in school at this age. Past year prevalence was highest among whites and respondents with high family income. The onset of hallucinogen use was most likely to occur between ages 15-19 years, regardless of birth cohort. These results indicate a stable pattern since hallucinogens were made widely available in the late 1960s, in which the transition from adolescence to adulthood has been the period of highest risk for hallucinogen use.